Constraining the carbon cycle in JULES-ES-1.0

Code to run analysis and generate figures for McNeall et al. (2022) “Constraining the carbon cycle in JULES-ES-1.0”

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0.1 Failure analysis

1 Visualising the ensemble range

It’s important to remember that the design of the experiment is multiplication factors of the original parameters. This might be important for the “hold” value in a sensitivity analysis, as the “standard” value and the median value of the ensemble will not be the same.

1.1 Wave00/Wave01 Ensemble behaviour in key (constraining) outputs.

Global mean for the 20 years at the end of the 20th Century. There is still a significant low bias on cVeg output.

1.2 What proportion of wave01 fall within Andy Wiltshire’s constraints?

Just under a third. Points at a significant model discrepency in cVeg

Of the 400 members of the wave01 ensemble, 128 pass Andy Wiltshire’s Level 2 constraints.

[1] 128
[1] 0.32

1.3 Exploring summary of constraint: Cumulative NBP

1.3.1 Carbon budget data

Section 2.5 in Friedlingstein et al. describes how the land carbon sink is estimated.

IPCC AR6 Chapter 5 states: “The net land carbon sink is taken as net biome productivity (NBP) and so includes any modelled net land-use change emissions. Further details on data sources and processing are available in the chapter data table (Table 5.SM.6).”

The GCP says: “The land sink is the average of several dynamic global vegetation models that reproduce the observed mean total land sink of the 1990s.”

AR6 Chapter 5 states: "The land carbon cycle components of historical ESM simulations show a larger range, with simulated cumulative land carbon uptake (1850–2014) spanning the range from –47 to +21 GtC, compared to the GCP estimate of –12 ± 50 GtC (Figure 5.23b).

2 How much are all select output constrained?

2.0.1 Constraint of output at level 2

Proportion of the initial range of model output that is covered by level 2 constrained ensemble (%):

                  npp                   nbp                 cSoil                  cVeg          lai_lnd_mean            rh_lnd_sum 
                 26.6                  55.1                  48.3                  23.5                  60.9                  26.0 
         fLuc_lnd_sum      fHarvest_lnd_sum     treeFrac_lnd_mean    shrubFrac_lnd_mean baresoilFrac_lnd_mean    c3PftFrac_lnd_mean 
                 51.5                  60.7                  88.3                  85.4                  52.9                  58.0 
   c4PftFrac_lnd_mean 
                 43.9 

2.0.2 Pairs plot of 2d projections of constrained output space.

2.1 Constraining to level 2 with the emulator